自分泌ATP/P2X1/Ca2+信号通路对脓毒症时中性粒细胞趋化的抑制作用及机制

中性粒细胞趋化功能受损是脓毒症患者感染难以控制的重要原因，但目前其机制尚未很好阐明。既往报道显示，胞外ATP作为损伤相关分子模式分子可抑制中性粒细胞趋化，我们的前期研究发现脓毒症动物血浆ATP水平升高并且中性粒细胞趋化功能受损，进一步的研究显示内毒素刺激后中性粒细胞通过分泌胞外ATP作用于自身P2X1受体，促进了细胞Ca2+内流并且抑制了细胞趋化，P2X1受体敲减部分恢复了细胞趋化（dHL-60细胞模型），因此我们推测自分泌ATP/P2X1/Ca2+信号通路可能与脓毒症时中性粒细胞趋化功能受损密切相关，但其详细机制目前仍不明确。本研究拟在前期研究的基础上，采用P2X1受体基因敲除小鼠，运用原子力显微镜、激光共聚焦显微镜等检测手段，进一步阐明中性粒细胞自分泌ATP/P2X1/Ca2+这一信号通路，并揭示其对脓毒症时中性粒细胞趋化的抑制作用及相关的分子机制，为脓毒症的抗感染治疗提供理论依据。

Impaired neutrophil chemotaxis toward infectious foci is an important reason for the uncontrollable infection in septic patients. However, the detailed mechanisms are still to be illustrated. Extracellular ATP, as a molecule of damage-associated molecular patterns, has been proved to inhibit neutrophil chemotaxis. Results of our preliminary experiments show that ATP level is increased in plasma of septic animals and neutrophil chemotaxis is inhibited. Further experiments indicate that the LPS-induced autocrine release of extracellular ATP inhibits neutrophil chemotaxis by activating P2X1 receptor and the subsequent Ca2+ influx. Knockdown of P2X1 receptor in dHL-60 cells partially restores neutrophil chemotaxis. Therefore, we speculate that autocrine ATP/P2X1/Ca2+ may be critical for the impaired neutrophil chemotaxis in sepsis. However, the detailed mechanisms of this pathway are still unknown. Based on the results of preliminary experiments, atomic force microscopy, laser scanning confocal microscope and other detecting techniques will be employed to further illuminate the neutrophil autocrine ATP/P2X1/Ca2+ pathway by using P2X1 receptor knockout mice. Meanwhile, the significance and mechanism of autocrine ATP/P2X1/Ca2+ pathway in sepsis-induced impaired neutrophil chemotaxis will be discovered to assist for the therapeutic anti-infection strategies for sepsis treatment.